This invention relates to a plate heat exchanger of the type comprising plates, which are joined in pairs closely adjacent each other and provided with corrugations forming passageways for the media flowing through the plate heat exchanger.
The plates joined in pairs closely adjacent each other are provided with grooves about their circumference and about the inlet and outlet portions. The grooves are intended to receive the gaskets, which in assembled state of the heat exchanger are pressed sealingly between the respective plate pair, thereby preventing leakage from the heat exchanger and distributing the media in the inlet and outlet portions.
At the type of plate heat exchanger comprising single plates, a gasket is attached between the plates, whereby each plate and therewith its gasket groove automatically rests against the gasket located behind in the assembled heat exchanger. At the heat exchanger comprising plates, which are arranged in pairs and already at the manufacture joined to each other, no gasket is provided between these two plates and, therefore, there is no support between them in the area of the gasket grooves. This involves the risk, that leakage arises in the heat exchanger between adjacent pairs of plates, due to the fact that the plates comprised therein and their gasket grooves can be pressed in against each other, for example at the mounting or due to the working pressure prevailing in the media in the heat exchanger.
When the joint between the two plates comprised in the pair is an edge weld or an outward directed folding, the space, which is located inside between the plates and compared to the heat exchanger with single plates has no gasket, permits a relatively free flow of the medium flowing between the plates arranged in pairs. This space, thus, acts in principle as a shunt line and lowers the effeciency degree of the heat exchanger.